Time-Continuous Sliding Motion Image Registration Using Stationary Velocity Fields for Respiratory Motion Interpolation

We propose an image registration model for computing a dense, piecewise diffeomorphic deformation map between 3D thorax images which incorporates sliding motion as often occurring in the pleural cavity. Our approach is based on stationary velocity fields and neural implicit representations, with a particular focus on facilitating motion interpolation. This allows for generating a time-continuous model of the respiratory cycle based on end-inspiration and end-expiration images. We investigate the effect of composing deformations in motion interpolation, using a hybrid technique to enforce domain alignment. We experimentally validate our approach for registration and motion interpolation between thoracic end-inspiration and end-expiration images.